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Posted: 8/13/2017 3:15:17 AM EDT
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I'm building a lightweight AR for my teenage cousin. I'm aiming for under or around 6.5 pounds. Most of my 16" carbines weigh 7-8 pounds.
I just picked up a ligthweight mid length faxon barrel. What other major components will drop the weight down? |
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You can easily achieve your weight goal, and at 6lbs you can do it on a decent budget.
Is there a certain configuration of AR you have in mind? What barrel did you get? Budget? What optics/sights? Planned use? Some reading to get you started, welcome to the madness Pics and build lists Lightweight build discussion, parts Parts data base |
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Assuming you want to use a standard forged upper/lower, and a full mass BCG, using the PWD I've roughly estimated a weight for an AR-15 that's a little over 5lb before adding a muzzle device or optic.
-Complete upper(used BCM in the PWD): 8.5oz --- You can save ~2oz by going with an upper without forward assist and up to another oz if you go with a polymer or light alloy -Stripped lower(used Spikes in the PWD): 8.4oz -- Again, you can save about 2oz by going with a lightweight lower, and a little more if you go with polymer or a light alloy -LPK(used PSA Classic LPK): 5.1oz -- You might be able to squeeze out an ounce if you go with ultra lightweight parts here; titanium everywhere, skeletonized mag release and bolt catch, etc. A polymer LPK would save you 3oz, but everything except for pins and springs will be polymer -Buffer Tube(used VLTOR milspec): 3.7oz -- Essentially no potential weight savings here -Stock(used MFT Minimalist): 6oz -- This is one of the lighter stocks available, but there are several options under 6oz, including the old CAR stocks -BCG(used S&W OEM): 11.3oz -- Significant weight savings is available, but there are two options. You'll have to pay a premium for Titanium parts, or you can save 2.5-3oz by going with an AIM lightweight or Faxon GUNNER BCG -BUIS(used Magpul MBUS): 2.5oz total -- ARMS, Spike's Micro, and Bobro Lowrider are lighter, but they're all pretty similar weight. Bobro Lowrider are the lightest, smallest dimensions, and made of 6061-T6(as are the Spike's) -Grip: 3oz -- I made an average. There are way too many grips and they're all really similar in weight. Some are lighter than 3oz, some are slightly heavier. It just depends on what grip you like -Handguard(used SLR Helix 13.7"): 8.5oz -- That weight includes the mounting hardware. This is light for an aluminum handguard. You can get lighter handguards, but at that point, you're heading into carbon fiber tube territory -Gas block(used Faxon ultra low-profile): 1.12oz -- You can shave about half of that weight off with a Master of Arms Titanium adjustable gas block -- recommended if you're going with a lightweight BCG -Buffer / Buffer spring(used Tubbs flat spring and Spike's ST-T1): 4.5oz -- The only weight savings you'll find here is if you've already gone for a light BCG and adjustable gas. You can grab a Taccom buffer for right around 1oz -Barrel: 22oz -- Faxon makes more than one 16" lightweight barrel. For the purposes of this build, I chose the heavier one to ensure that if anything, the total weight would be high rather than low. Total weight: 5.26lb If we assume 2.5oz for something like a M4-72 or BCM Mod0 for the muzzle device, that leaves 18oz for a scope/mount or red dot/mount. You'll be just over the 6.5lb limit with an Aero Precision ultralight mount and something like a Leupold Mk VI 1-6(~6.67lb), but if you get a Fortis F1 mount with something like a Holosun, Aimpoint T1, Primary Arms, Bushnell TRS-25, you'll be under 6lb. Now, on to where you can save the most weight. Getting something like a Smoke Composites stock would save you ~5.7oz comparing to the list I made above. The stock is the buffer tube, so that weight is taken out entirely, and the whole thing weighs 4oz. If you're in the build process right now, or you're planning a build and you aren't going to use a buffer tube that you've got lying around, then this would be a great opportunity to save weight. Obviously there's no kind of cheek weld with this stock, though you could wrap it in some foam if that's an issue. The place that I would be looking at most to save weight is reciprocating mass. If you get a Faxon GUNNER BCG, the Taccom buffer, and the Master of Arms adjustable gas block, you're saving, again, a little over 5 and a half oz, but the result of this change is that you'll be tuning your rifle, meaning it'll feel so much softer while shooting. On top of that, you're shaving weight off of what's typically center of mass, so the weight savings will be more noticeable in use than if you made similar changes to the stock area. If there's no budget, you could save another 5oz by getting a lightweight upper/lower like 2A-Armament's Balios Lite or V7's 2055 Enlightened. |
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Warms the heart to see the PWD employed in threads like this.  It's designed to be a part selection tool and will definitely help you hit pretty much any goal weight that is possible with parts that are available. |
| Barrels are one section of the pwd that is, to me, still under developed. If you can think of any good manufacturers that should be added, plmk and I'll dig up what I can. There have been a TON of off the shelf barrel options for the AR over the years, right now that "sheet" is somewhat limited on that front. |
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I'm on the PWD almost daily as well. Such a great resource.
There is also a light weight fighting gun thread running here. Many posted builds running full weight OS at or below your target weight goal. |
| Great choice on the Faxon barrel. I am just finishing up a Recce type build with a Faxon Socom barrel. It turned out to be a really light rifle. Most of the weight is in the barrel so the pencile barrel is a huge savings right there. Round it off with a light rail and stock and you can have a light build and not need to spend a ton of money on light weight small parts. I used a UTG Pro SS rail and it is very slim and light. For a stock Mission First Tactical or Magplu MOE are good choices. |
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With a faxon pencil barrel, you can do 5 lbs with a reddot with no expensive parts.
If there is an expensive part, it will be an upgraded adjustable gas block. http://www.ar15.com/forums/t_3_118/625051_ULTRA-light-weight-picture-thread----the-under-6-crowd-.html&page=30#i7453607 |
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With a faxon pencil barrel, you can do 5 lbs with a reddot with no expensive parts. If there is an expensive part, it will be an upgraded adjustable gas block. http://www.ar15.com/forums/t_3_118/625051_ULTRA-light-weight-picture-thread----the-under-6-crowd-.html&page=30#i7453607 |
This is what a 16" middy that weighs in at 6lb 12oz looks like. Achieved without the use of a pencil barrel, short or skeletonized rails or an anorexic buttstock. Still rockin' steel BUIS, forged aluminum ambi-bolt release and grip stop. There is even a bottle of Slip2000 oil, a small jar of grease, a torx wrench and a spare CR2032 stored in the grip.
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This is what a 16" middy that weighs in at 6lb 12oz looks like. Achieved without the use of a pencil barrel, short or skeletonized rails or an anorexic buttstock. Still rockin' steel BUIS, forged aluminum ambi-bolt release and grip stop. There is even a bottle of Slip2000 oil, a small jar of grease, a torx wrench and a spare CR2032 stored in the grip. https://i11.servimg.com/u/f11/12/63/91/01/20170810.jpg I have a similiar carbine, but with a mid weight barrel, 15" rail and all the rest is standard. It weighs in 7lb 6 oz. I assume it's the California stock. |
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But HOW master? |
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@Creature aluminum bolt release? Manufacturer? Without compromising on bbl, rail length, and stock, you could prolly still pretty easily get to sub 6lbs... |
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This is what a 16" middy that weighs in at 6lb 12oz looks like. Achieved without the use of a pencil barrel, short or skeletonized rails or an anorexic buttstock. Still rockin' steel BUIS, forged aluminum ambi-bolt release and grip stop. There is even a bottle of Slip2000 oil, a small jar of grease, a torx wrench and a spare CR2032 stored in the grip. https://i11.servimg.com/u/f11/12/63/91/01/20170810.jpg |
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Quoted:The bolt release is a Phase 5 EBRV2, so it's actually constructed from steel. I have no interest in spending more money...or removing parts for that matter...simply to achieve a sub-6# rifle. |
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check out V7 Weapon Systems, they have a wide range of lightweight AR15 parts. 5.7 LBS WITH an ACOG and Lrue MBT trigger . it will also shoot a appleseed qualificaition (I just wanted to be sure it would before I gave it to my wife) Attached File |
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I got a DANM good start using them. 5.7 LBS WITH an ACOG and Lrue MBT trigger . it will also shoot a appleseed qualificaition (I just wanted to be sure it would before I gave it to my wife) https://www.AR15.Com/media/mediaFiles/216165/IMG_1016-294249.JPG |
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We spy a Faxon barrel on that. Great choice and great build! lower is magnesium lower by mag tech, MBT trigger group, titanium takedown pins, titanium end plate, no name tube, and MOE buttstock. |
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Upper is faxon ultra light weight 16, v7 titanium hider, DSA light weight upper(with titanium FA), faxon light weight BCG, adjustable titanium gas block(forget who made it), Acog and mount, and Clark custom carbon fiber guard lower is magnesium lower by mag tech, MBT trigger group, titanium takedown pins, titanium end plate, no name tube, and MOE buttstock. would appreciate your feedback on how that lower receiver was to build up? Have you compared to current Fostech? |
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@fsjdw2 would appreciate your feedback on how that lower receiver was to build up? Have you compared to current Fostech? Quoted:
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Upper is faxon ultra light weight 16, v7 titanium hider, DSA light weight upper(with titanium FA), faxon light weight BCG, adjustable titanium gas block(forget who made it), Acog and mount, and Clark custom carbon fiber guard lower is magnesium lower by mag tech, MBT trigger group, titanium takedown pins, titanium end plate, no name tube, and MOE buttstock. would appreciate your feedback on how that lower receiver was to build up? Have you compared to current Fostech?  ). Send me a FosTech and ill build it up and compare... lol
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